John Lewis was the 23-year-old son of Alabama sharecroppers and a veteran of the civil rights movement when he came to the capital 50 years ago this month to deliver a fiery call for justice on the steps of the Lincoln Memorial.

Lewis' urgent cry - "We want our freedom, and we want it now!" - was eclipsed on the steps that day by the Rev. Martin Luther King Jr.'s "I Have a Dream" speech. But two years later, after Alabama State Police officers beat him and fractured his skull while he led a march in Selma, he was back in Washington to witness President Lyndon B. Johnson sign the Voting Rights Act of 1965.

Today, Lewis is a congressman from Georgia and the sole surviving speaker from the March on Washington in August 1963. His history makes him the closest thing to a moral voice in the divided Congress. At 73, he is still battling a half-century-old fight.

With the Voting Rights Act in jeopardy now that the Supreme Court has invalidated one of its central provisions, Lewis, a Democrat, is fighting an uphill battle to reauthorize it.

He is using his stature as a civil rights icon to prod colleagues like the Republican leader, Eric Cantor, to get on board. He has also met with the mother of Trayvon Martin and compared the shooting of the unarmed Florida teenager to the 1955 murder of 14-year-old Emmett Till.

Lewis has an answer for those who say the election of a black president was a fulfillment of King's dream: It was only "a down payment," he said.

"There's a lot of pain, a lot of hurt in America," Lewis said in his office on Capitol Hill, which has wall-to-wall black-and-white photographs of the civil rights movement. Current events, he said, "remind us of our dark past."

But Lewis, a longtime practitioner of civil disobedience, is also encouraged. He said he found it gratifying to see peaceful throngs "protesting in a nonviolent fashion" after George Zimmerman was acquitted in Martin's killing.

Now Lewis is introducing himself to a new generation by telling the story of his life as a Freedom Rider in "March," a graphic novel that is being released this week. The book's co-author is a young aide, Andrew Aydin, who pestered Lewis until he agreed to cooperate; it is modeled on a 1958 comic about King, which inspired early sit-ins.

Each year, Lewis leads an emotional re-enactment of the so-called Bloody Sunday march across Selma's Edmund Pettus Bridge, where the brutal police response horrified the nation.

Cantor participated this year, bringing his college-age son, and said he had come away "very moved" - a sentiment that Lewis will no doubt play on during negotiations over a new bill.

On Aug. 24, at an anniversary march on Washington, Lewis will speak again at the Lincoln Memorial.